Containers are filled with fluent materials in a production line as they are moved along by a conveyor. The containers, e.g. bottles, are displaced from a supply to a filling station, then to a capping station and may pass through control checkpoints, labeling machines and the like. Such systems are used in the packaging of food, pharmaceuticals, beauty products, and numerous other consumer items.
A typical conveyor has at least one chain that carries a succession of so-called cell plates that each have a seat adapted to fit complementarily with one or more of the containers. Thus the containers are loaded onto the respective cell plates where they reside as the conveyor moves them through the various treatment stations until the finished package is picked off the conveyor, typically at the downstream end of an upper stretch. Then the empty plates travel back, normally upside down, on the lower stretch to the upstream end where more containers are loaded on and the cycle is repeated.
The main problem with this type of installation is that when the container size changes it is necessary to refit the conveyor with appropriately sized cell plates. This is typically a lengthy process entailing withdrawing holding screws at each plate, taking the plate off, putting the new plate in position, and securing the new plate in place with the screws. Obviously the down time for such an operation is considerable, but since the plates have to be very solidly linked to the conveyor so they do not shift thereon it is normally considered necessary to provide an attachment that cannot be undone easily. Furthermore the plates have to be exactly positioned and equispaced along the conveyor so that the containers they will hold are perfectly positioned in the various treatment stations.
In addition to the considerable down time for plate changing, this system has the disadvantage that the plates are often damaged by the tools used to make the changeover. Furthermore the protruding heads of the bolts are a trap for dirt that can foul the product being prepared.
German patent 3,538,993 uses a robot-type manipulator to withdraw the screws holding the cell plates in place and to lift off the freed cell plates by means of a suction grab and put then in storage. Another manipulator lifts a new plate off a supply and fits it in position while the screws are again set back in place by the robot. While this system does avoid the problem of dealing with slow manual labor, it still is relatively slow and has the above-mentioned problems with hygiene. In addition the equipment is very complex and expensive.
In German patent 3,743,278 a conveyor is provided where the attachment screws are replaced by individual latches on the cell plates. Normally vertical studs provided on the chain acting as conveyor element are gripped by the latches on the plates. While this system eliminates the problems with the prior-art screws, it entails a fairly complex construction of the individual cell plates that elevates the cost of the equipment considerably.